We describe a new and accurate algorithm for computing translational gradients of incoming radiance in the context of a ray tracing-based global illumination solution. The gradient characterizes how the incoming directional radiance function changes with displacement on a surface. We use the gradient for a smoother radiance interpolation over glossy surfaces in the framework of the radiance caching algorithm. The proposed algorithm generalizes the irradiance gradient computation by [Ward and Heckbert 1992] to allow its use for non-diffuse, glossy, surfaces. Compared to previous method for radiance gradient computation, the new algorithm yields better gradient estimates in the presence of significant occlusion changes in the sampled environment, allowing a smoother indirect illumination interpolation.
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机译：我们描述了一种新的，精确的算法，用于在基于射线跟踪的全局照明解决方案的上下文中计算入射辐射的平移梯度。梯度表示入射的定向辐射函数如何随表面上的位移而变化。在辐射缓存算法的框架中，我们将渐变用于在光滑表面上进行更平滑的辐射插值。提出的算法概括了[Ward and Heckbert 1992]的辐照度梯度计算，以允许其用于非漫射，有光泽的表面。与以前的辐射梯度计算方法相比，在采样环境中存在明显的遮挡变化的情况下，新算法可产生更好的梯度估计，从而可以实现更平滑的间接照明插值。
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